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authorStephen Warren <swarren@nvidia.com>2013-05-30 09:59:39 -0600
committerMark Brown <broonie@linaro.org>2013-06-01 19:46:16 +0100
commit4dd9572abc224019a042b662fb0eececca283cb9 (patch)
tree920636df3ca9198c43fd89973703b6e177cb27cc /include/linux/spi
parent6051426fd0538eac4e28c55a08e4f4fb1c709b65 (diff)
spi: fix undefined behaviour in SPI_BPW_RANGE_MASK
The parameters to SPI_BPW_RANGE_MASK() are in the range 1..32. If 32 is used as a parameter, part of the expression is "1 << 32". Since 32 is >= the size of the type in use, such a shift is undefined behaviour. Add macro SPI_BIT_MASK to Implement a special case and thus avoid undefined behaviour. Use this new macro rather than BIT() when implementing SPI_BPW_RANGE_MASK(). This fixes build warnings such as: drivers/spi/spi-gpio.c:446:2: warning: left shift count >= width of type [enabled by default] SPI_BPW_MASK() already avoids this, since its parameter is also in range 1..32, yet it only shifts by up to one less than the input parameter. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'include/linux/spi')
-rw-r--r--include/linux/spi/spi.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 173725622252..3e9479134d9d 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -309,7 +309,8 @@ struct spi_master {
/* bitmask of supported bits_per_word for transfers */
u32 bits_per_word_mask;
#define SPI_BPW_MASK(bits) BIT((bits) - 1)
-#define SPI_BPW_RANGE_MASK(min, max) ((BIT(max) - 1) - (BIT(min) - 1))
+#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0UL : (BIT(bits) - 1))
+#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min))
/* other constraints relevant to this driver */
u16 flags;